SharpCap Wide Swings After Polar Alignment "Could not Solve" Message

[DanielRA]

Hi all. I posted this on Cloudy Nights and it was suggested that I reach out there:

You ever have one of those nights when you just want to kick you mount over and take up a new hobby like bird watching? I sure did last night. After a QHY driver issue gave me a hard time last weekend I was excited to get back to some narrowband imaging with the Rosette Nebula. After going through my set up routine I was ready to polar align. I first roughed in Polaris and launched SharpCap using my QHY163M to run the alignment. I've done this dozens of times already so why should tonight be any different, right? I go through the routine, solve, rotate 90 degrees, and here's where I ran into a problem, spent an hour trying to make it right, and then decided to take up bird watching. Okay, I didn't kick over my mount in frustration but it took everything I had NOT to. Here's what would happen: SC would solve and give me the left/right, up/down directions. I would make the adjustments and invariably get "could not solve." Thing is, after it would solve again I'd be waaaaaaaaay off usually the opposite direction. For example, I'd solve at Left: 3'33", Up: 44", so I'd make the adjustments and eventually run into a "could not solve" message so I would stop adjusting and wait for a solve. The next solve that comes up would have something like Right: 16'22", Down: 2'16". How is that possible if I didn't even touch anything?

Tonight, through some miracle I managed to get a polar alignment error of 17" which I guess is fine though I can usually get in under 10". This is after about an hour of trying both the QHY and my ASI290 guide camera (OAG), 1x1 and 2x2 binning, 2 seconds, 4 seconds, sliding the gain all over the place... Just to make sure I checked my notes from last weekend and sure enough not only did I get a PAE of 10" it only took me about 10 minutes or so. Any ideas? I checked the mount and scope to make sure nothing was moving funny, I ran an auto-focus routine as usual prior to running polar alignment, seeing is no different than usual, so I don't get it.

For reference I have the Star Detection settings at the default with digital gain turned off and minimum star size at 4.

[admin]

Hi,

This sort of problem almost always boils down to not finding the right number of stars to let the plates solving do its job. Sometimes the solution is as simple as turning up the camera exposure or gain. There are a lot of hints to help you out that can be found on the polar alignment troubleshooting page here: https://www.sharpcap.co.uk/sharpcap/fea ... leshooting

Hope this information helps, if not then please post back. Robin